Refrigerating apparatus



Dec. 29,1942. A. A. MCCORMACK 2,396,632

REFRIGERATING APPARATUS Filed Sept. 28, 1940 2 Sheets-Sheet l INVENZQR.

ATTORNEY.

A. A. M CORMACK 2,306,632 REFRIGERATING APPARATUS I Filed Sept. 28, 19402 Sheets-Sheet 2 9n 0d 0 n l w I i w m L M I v oi k ' INVENTO W4 4 M 94%ATTORNEY.

Dec. 29, 1942.

UNITED STATE Patented Dec. 2 9, 1942 REFRIGERATING APPARATUS Alex A.McCormaok, Dayton, Ohio, assignor to General Motors Corporation, Dayton,Ohio, a corporation of Delaware Application September as, 1940, SerialNo. 358,893

s PATENT" OFFICE such as aluminum.

Claims.

as the coeflicient of expansion of iron, it has not been consideredpossible to make use of the lighter weight materials in any unit inwhich a refrigerant tight joint must be provided at the juncture of thetwo different types of metal.

Attempts have also been made to reduce the weight of a rotary compressorby increasing the capacity of a given weight compressor by increasingthe speed of the compressor. However, these attempts have also provenunsuccessful prior to my invention, due to certain difficultiesencountered in lubricating and cooling the various parts of thecompressor mechanism. It is an object of this invention, therefore, toprovide a compressor construction which overcomes these problems whichhave heretofore prevented the use of light weight, high speed, largecapacity, rotary compressors. Y

A further object of .this invention is to provide an improvedarrangement for lubricating the compressor parts. 4

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. l is a view, partly diagrammatic, showing a refrigerant systemembodying my invention;

Fig. 2 is a cross sectional view of the. compressor shown in Figs. 1 and3, and taken on the line 2-2 of Fig. 3;-and

Fig. 3 is a cross sectional view of the compressor shown in Figs. 1 and2, and is taken-on the line 33 Of Fig. 2.

Referring now to Fig. 1, the reference numeral I ll designates acompressor which may be driven by means of an internal combustion engine(not shown) or any other suitable prime mover. The compressed gas leavesthe compressor via the line [2 leading to the condenser I4 wherein thecompressed refrigerant gas is converted into liquid' refrigerant. Liquidrefrigerant leaves the condenser I! through the line It which conveysthe liquid refrigerant into a shaft seal cooling chamber I8 formed inpart by the aluminum casting 20. The refrigerant leaves the chamber 18through line 22 which leads to the heat interchanger 24. After leavingthe heat interchanger 24, the refrigerant is required to flow through afixed restrictor 26 which may be of the capillary tube type or of thetype disclosed in the Kucher patent, No. 2,063,745. After leaving thefixed restrictor, the refrigerantenters the evaporator 28 wherein therefrigerant is converted into vapor. The refrigerant vapor leaves theevaporator -through the line 30 which is connected to the outer passage32 of the heat interchanger 24. Inasmuch as the refrigerant vaporleaving the evaporator 30 is at a relatively low temperature, it willserve to re-liquefy any high pressure refrigerant which may have beenvaporized in the chamber l8. After leaving the interchanger 2 5,

the low pressure vapor is conveyed to the intake of the compressor Illthrough the line 34.

Referring now to Fig. 3, in which a cross section of the compressor isshown, the reference numeral 40 designates. ah aluminum casting which issecured to the aluminum casting 20 by means of cap screws 42. A gasket46, of any suitable material, such as neoprene, is provided between thealuminum casting 40 and the aluminum casting 20, so as to make the jointbetween the two castings gas tight. Inasmuch as the castings 20 and 40are both made from aluminum, both will expand and contract atsubstantially the same rate in response to temperature changes.

The compressor mechanism proper is supported within the chamber formedby the aluminum.

castings 20 and 40 and includes an iron casting 46 bolted to thealuminum casting 20 by means of the cap. screws 41. The iron casting 46is provided with a bearing extension 48 in which the main compressorshaft 50 is journaled. The bearing extension 48 is recessed at 52 so asto provide a recess for the shaft seal which comprises a stationarysealing ring 54 carried by the bearing extension 48 and a movablesealing ring 58 which rotates along with the shaft 50. The stationaryring 54 is held in place by means of a metal washer'fl which in turn isheld in place by means of the cap screws 68. The-movable ring 56 issealed to the shaft 50 by means of the neoprene ring 58 which iscompressed into sealing engagement with the shaft 50 and the ring 56 bymeans of the spring washer 60. The washer 60 abuts against the shoulder62 provided on the shaft 50. ..'.Ihe

shaft 50 may be driven by any suitable means (not shown) such as anelectric motor or an and includes the main cylinder it which is se- 5cured to the iron casting 45 by means of cap screws 52. The rotorelement 74 is provided with the usual guideways for the vanes 16. Vanesis may be of cast iron construction or the equivalent,

' but the shoes 78 are preferably made of sintered i0 iron. There areseveral advantages in using sintered iron shoes. One advantage is thatthe sintered iron shoes may be made very cheaply without a great deal ofmachining since it is possible to size a sintered iron shoe of this typemerely by pushing it through a sizing die. Another advantage' of using asintered iron shoe is that a shoe of this type is substantially selflubricating in that a certain amount of lubricant is absorbed by thesintered iron, and this lubricant is fed to the wearing surfacesdirectly through the pores of the sintered iron.

' The iron casting 46 forms one end of the com-- pression chamber,whereas the iron casting forms the other end of the compression chamber.2

As best shown in Fig. 2, the low pressure refrigerant vapor enters thecompressor through the screened inlet 52. The entering vapor passesthrough the checir valve M on its way to the main inlet port at of thecompressor proper. In order to 30 prevent any of the high pressurerefrigerant gas surrounding the compressor cylinder i0 from entering thelow pressure inlet of the compressor a neoprene gasket 88 is providedbetween the main cylinder i0 and the inlet pipe B9. The gasket 85 5 ismounted within a tapered recess 90 provided in the side wall of thecompressor cylinder it]. The gasket 88 is also tapered a small amountwhereby as the conduit 88. is forced into the tapered recess of thegasket 88, a fluid tight joint 40 is provided. The low pressure vaporentering the compressor through the inlet port 86 is compressed in theusual well-known manner which needs no further explanation. Thecompressed gas normally'discharges through the outlet port 92 which isprovided with the usual form of valve 94. Inasmuch as there may be timeswhen the pressure within the main compression chamber exceeds thedischarge pressure before the outlet port 92 is uncovered, I haveprovided a special relief port 9B which is normally closed by the valveelement 38. This relief valve 98 prevents excessive pressures frombuilding up within the main compression chamber. The compressed gasleaving the outlet port 92 discharges directly into the chamber I00formed between the aluminum casting 40 and the iron casting 45. Inasmuchas the chamber I8 is normally filled with high pressure liquidrefrigerant and the chamber I00 is filled with refrigerant gas at thesame pressure; the tendency for leakage between the chamber IB and thechamber I00 is very little, This is especially true in view of the factthat the chamber I 8 is filled with liquid which helps to seal the jointbetween the aluminum casting 20 and the iron casting 46. By virtue ofthis particular arrangement-it is possible to use aluminum for the outercasing and cast iron for the main dividing wall 46. This is possiblenotwithstanding the fact that the coefficient of expansion for aluminumis almost twice as great as the coemcient'oi expansion of iron.Furthermore, the presence of a single body of liquid refrigerant'indirect thermal exchange with both the iron casting 46 and the aluminumcasting 20 prevents large fluctuations in the temperature of 7 lubricantsupply I02 in the chamber I00. Lubricant from the supply I02 enters thelubricant supply passages adjacent the bottom of the cylinder at I05.Lubricant entering at I04 is conveyed to the bearings through thepassages I06 and E08. Inasmuch as the main body of lubricant W2 is underhigh pressure, this lubricant is automatically fed to the bearingsthrough the oil feed passages H06 and I08.- Oil flowing through thepassage it tends to lubricate the right end of the four-vane rotor 14 asviewed in Fig. 3 and also serves to lubricate the right bearing of theshaft 56. An appreciable amount of lubricant will find its way along thebearing 50 into the end chamber Ii0 from whence a portion of thelubricant is supplied to the lubricant passage H2, from whence thelubricant finds its way into the low pressure side of the compressor.Another portion of the lubricant entering the end chamber I I0 issupplied to the lubricant passage I it formed by boringout the center ofthe shaft 50 as shown in Fig. 3. The lubricant flowing through thepassage H4 enters the shaft seal cavity 52 provided at the left end oi.the shaft 50. Lubricant flowing through the passage. I08 serves tolubricate the main bearing formed by the iron casting 46 and also servesto lubricate the left end of the four-vane rotor i4.

As shown in Fig. 3, cone-shaped cavities H8 and H8 are provided in theend walls of the castings 46 and respectively, so as to facilitatelubrication of the moving parts. A certain amount of the lubricantentering the passage I08 will flow along the shaft into the shaft sealcavity 52 from whence the lubricant returns to the low pressure portionof the compression chamber through the lubricant passage H0. The inletto the passage I20 is provided at a point in proximity to the mainsealing surfaces of the shaft As pointed out hereinabove, the main bodyof lubricant I02 is subjected to high side pressure, whereas thepressure within'the compression chamber adjacent the discharge ends ofthe lubricant passages Ii! and I20, is substantially equal to thelowside pressure with the result that the difference in pressures cuuses'anappreciable amount of lubricant to be 'fed to all of the surfaces whichrequire lubrication. The sintered iron shoes I0 help to distribute thelubricant to the surfaces contacting the shoes and are capable ofretaining a small reserve supply of. lubricant during periodsof shutdown. This reserve supply of lubricant serves to lubricate the shoesurfaces when the compressor first starts up after a period ofshut-down.

By virtue of the above described lubricating arrangement, it will. benoted that the left end of the shaft 60 is subjected to atmosphericpressure and is also subjected to pressure by the shaft seal spring 80.The combined pressures of the atmosphere and the shaft steel spring 60substantially equal the pressure exerted against the right end of theshaft by the lubricant in the chamber IIO when the compressor is inoperation. This balance between the pressures at the two ends of theshaft very materially reduces the 'wear on the compressor parts whichwould otherwhereby the danger of leakage at the shaft seal is greatlyreduced.

While I have disclosed the use of aluminum castings for the main casingelements, it is to be understood that in referring to the use ofaluminum that other light weight materials such as the magnesium alloys,duralumin and the like could be used.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A cast iron frame member, compressor mechanism secured to said framemember and having a shaft journaled in said frame member, a firstaluminum casting enclosing a first portion of said frame member andforming with said frame member a first refrigerant chamber, a secondaluminum casting secured to said first aluminum casting enclosinganother portion of said frame member and forming a second refrigerantchamber, an inlet port for said compressor, an

outlet port for said compressor discharging into one of said chambersand means for supplying high pressure liquid refrigerant to the other ofsaid chambers whereby said liquid refrigerant is in thermal exchangewith said frame member and one of said ahuninum castings.

2. In combination a frame member, compressor mechanism carried by saidframe member and including a tapered inlet port, housing means securedto said frame member and including an opening spaced from said taperedinlet port, means for conveying refrigerant from said opening to saidinlet port comprising a refrigerant conduit secured to said housingmeans and removably projecting into said tapered inlet port. and gasketmeans within said tapered port surrounding said conduit means.

3. In combination a frame member, compressor mechanism carried by saidframe member and including a tapered inlet port, housing means securedto said frame member and including an opening spaced from said taperedinlet port, means for conveying refrigerant from said opening to saidinlet port comprising a refrigerant conduit secured to said outercasting and removably projecting into said tapered inlet port, andgasket means within said tapered port surrounding said conduit means,and a checkwe supported within said conduit for preventing fluid fromflowing from said inlet port through said opening.

4. In a refrigerant compressor, casing means, compressor mechanismwithin said casing, a drive shaft for said compressor mechanism havingone end projecting through one wall of said casing and subjected toatmospheric pressure, shaft seal means preventing escape of refrigerantbetween said shaft and said casing, said shaft seal means includingspring means tending to move said shaft inwardly of said casing, a fluidchamber adjacent the inner end of said shaft, and means for maintainingthe pressure of th fluid in said chamber at a value whereby the pressureexerted by said fluid against the inner end of said shaft substantiallyequals the inward pressure exerted against said shaft by said springmeans and the atmosphere.

5. Refrigerating apparatus comprising in combination, an evaporator, acompressor for withdrawing refrigerant vapor from said evaporatorcomprising a main frame having one coefficient of expansion and an outercasing secured to said frame and having a different coefficient ofexpansion, a condenser for condensing refrigerant discharged from saidcompressor, and means for conveying liquid refrigerant condensed by saidcondenser into thermal exchange relationship with said frame and saidcasing at the juncture of said frame and said casing, said compressorincluding a driving shaft projecting through said outer casing, and ashaft seal between said shaft and said casing having the stationaryportion thereof carried by said main frame.

6. A compressor mechanism comprising in combination, a cast iron framemember, a compressor shaft journaled in said frame member, shaft sealmeans carried by said frame member, cast aluminum means secured to saidframe member forming with said frame member a cooling chamber,compressor mechanism operated by said shaft and secured to said framemember, and cast aluminum means enclosing said compressor mechanism andforming with said frame member a lubricant and refrigerant chamberenclosing said mechanism.

7. A cast iron frame member, compressor mechanism secured to said framemember and having a shaft journaled in said frame member, a firstaluminum casting enclosing a first portion of said frame member andforming with said frame member a first refrigerant chamber, a secondaluminum casting secured to said first aluminum casting enclosinganother portion of said frame member and forming a second refrigerantchamber, and means for supplying high pressure liquid refrigerant to oneof said chambers whereby said liquid refrigerant is in thermal exchangewith said frame member and one of said alumium castings.

8. In combination a frame member having one coefficient of expansion,compressor mechanism carried by said frame member and including atapered inlet port, housing means having a different coefficient ofexpansion secured to said frame member and including an opening spacedfrom said tapered inlet port, means for conveying refrigerant from saidopening to said inlet port comprising a refrigerant conduit secured tosaid outer housing and removably projecting into said tapered inletport, and gasket means Within said tapered port surrounding said conduitmeans.

9. In combination, pump mechanism including a frame member having onecoefficient of expansion and provided with an inlet port, a housingmember having a different coefficient of expansion than said framemember and enclosing said pump mechanism, means for conveying a fluid tobe pumped from outside said housing to said inlet port comprising aconduit having a rigid connection to said housing member and a yieldableconnection to said frame member.

10. A refrigerant compressor comprising in combination, a cast ironframe member, a cast iron compressor cylinder secured to said framemember, a compressor shaft journaled in said frame member, a multiplevane rotary compressing means rotated by said shaft and operating withinsaid compressor cylinder, each of said vanes comprising a cast iron bodyportion and a sintered iron shoe portion, shaft seal means forpreventing the escape of lubricant along said shaft, an aluminum casingsurrounding said shaft seal means and forming with said frame member acooling chamber, a second aluminum casing secured to said first casingand forming with said frame member a lubricant and high pressurerefrigerant reservoir into which the compressed gas is discharged, meansfor feeding lubricant from said high pressure reservoir to said shaftseal means, and means for supplying lubricant from said reservoir tosaid multiple vane compressing means including said sintered iron shoes,said cooling chamber being arranged to cool said shaft seal and to coolthe juncture of said frame memher with said first named aluminum casing.

ALEX A. MCCORMACK.

